1. Field of the Invention
The present invention relates generally to optical measurement systems, and more specifically, to an active sensor illumination and detection apparatus for performing sample measurements using associated detector/illuminator groups integrated on one or more substrates.
2. Background of the Invention
One-dimensional and two dimensional measurement and inspection of samples is commonly performed in many industries, including biotechnology, semiconductor, micro electro-mechanical systems (MEMS) and others. For example, in the biotechnology industry, fluorescence measurements are used to determine the response of biological matter to illumination, thus revealing information about the composition and structure of a sample. Typically, for biological fluorescence tests, a sample or a material that is introduced to a sample is “tagged” with a fluorescent compound, the sample is illuminated with a laser, and the resulting fluorescent emissions are mapped to determine the locations of the fluorescent compound after interaction with the sample. For example, a prospective cancer drug may be tagged with a fluorescent compound and introduced to a sample having cancerous tissue. Then the sample is washed to remove excess fluorescent compound. The sample is illuminated and resulting fluorescent emissions are mapped to determine whether or not the prospective drug has bound to the cancer active sensor cells.
The above-described process is typically performed on a bio array, which may be a sample of DNA, gene chips including multiple DNA strands, microtiter plates with wells filled with various biocompounds, or microfluidic lab-on-a-chip devices. In each case, the device or sample is illuminated, typically by a scanning laser or filtered light source. Then, the resulting fluorescence (or lack thereof) is mapped. The mapping is typically performed by either a scanning confocal microscope (SCM) or by imaging onto a charge-coupled-device (CCD) sensor.
The disadvantages of the above-described systems and methods are long scanning times and moving parts for the SCM-based approach and lack of sensitivity and poorer spatial resolution for the CCD-based approach. A third alternative has been implemented, using a scanning laser and a photomultiplier tube for detection, but the cost of the scanning laser and detectors is a disadvantage, as well as the requirement of a moving mechanism.
In another application, in the inspection of color quality in materials, for example dye color, the sample may be illuminated and the sample's optical behavior measured to determine the properties of the sample. Measurement may be made of reflectivity, absorption, transmission, secondary emission or other optical property in order to determine sample characteristics. In order to measure a sufficient field of view, precise control over the color and angular spectrum must be maintained for both illumination and detection systems. The above requirements necessarily add tremendous complexity to any measurement tool.
In the field of MEMS and semiconductor manufacture, repetitive patterns are inspected for defects or anomalies. The device under inspection is illuminated and scattered and/or reflected light is imaged to determine properties of the device under inspection. Such illumination and detection techniques can be quite complex in order to provide the necessary sensitivity and resolution.
Therefore, it is desirable to provide an alternative method and system for providing active illumination and detection for one-dimensional and two-dimensional inspection of samples having low cost, sufficient resolution, high sensitivity and high scanning speed for a broad range of applications.